Comparison of amantadine, orphenadrine, and placebo in the control of phenothiazine-induced Parkinsonism

Synopsis A double-blind comparison was made of the effects of amantadine hydrochloride, orphenadrine hydrochloride, and placebo in the control of the effects on the extrapyramidal nervous system of fluphenazine decanoate. Patients were assessed with regard to the main symptoms of Parkinsonism, the leading clinical signs, performance in walking, writing and squeezing, changes in mood, and unwanted effects of medication. Neither of the pharmacologically active substances was superior to placebo. Attention is drawn to the paucity of evidence for the effectiveness of anti-cholinergic drugs in both Parkinson's disease and in drug-induced Parkinsonism. The special difficulties in performing trials of substances used in relieving the unwanted effects of other drugs are discussed in relationship to defects in methodology in both this and earlier trials. The findings of the present study are not conclusive but show a clear need for further research in this field. The possible theoretical and practical importance of such research is discussed.